Suppression of natural killer cells in the presence of CD34+ blood progenitor cells and peripheral blood lymphocytes

AbstractMobilization of CD34+ peripheral blood progenitor cells (PBPCs) with granulocyte-colony stimulating factor (G-CSF) may induce functional alterations in peripheral blood lymphocyte (PBL) subsets. We and others have shown that natural killer (NK) cells from PBPC collections are less expandable in vitrothan those obtained during steady-state hematopoiesis. We show here that the extent of this proliferation deficit is related to the number of circulating CD34+ cells in vivo at the time of PBPC apheresis. Likewise, addition of autologous CD34+ cells to unseparated PBL reduced the expansion of the NK-cell subset by 22.2% ± 6.0% (n = 10; P <.005). In contrast, when using purified NK cells, their proliferation remained unimpaired by autologous CD34+ cells. Supernatants from CD34+ cells cultured with autologous PBLs had an inhibitory effect on proliferation of purified NK cells (n = 16; P = .03), indicating that an interaction between CD34+ cells and lymphocytes is essential for the suppressive effect on NK cells. To investigate the role of T cells in this interaction, intracellular cytokines were determined in T cells cultured for 7 days with or without autologous CD34+ cells. When cultured with CD34+ cells, the frequency of IL-2–producing CD4+ and CD8+ T cells was reduced by 19% and 24%, respectively, compared with T cells cultured alone (n = 7; P = .016). Interferon-γ—producing T cells were slightly reduced (P = not statistically significant [ns]). Finally, the influence of T cells and NK cells on the recovery of myeloid colony-forming cells (CFU-GMs) from purified CD34+ cells was examined. In the presence of T cells, 16% ± 6% of the input CFU-GM recovered after 7 days, compared with 5% ± 4% in the presence of NK cells (n = 5; P = ns). Our findings point to an inhibition of NK-cell proliferation mediated by an interaction of CD34+ cells and T cells occurring during PBPC mobilization with G-CSF

Clinical impact of DNMT3A mutations in younger adult patients with acute myeloid leukemia: results of the AML Study Group (AMLSG)

In this study, we evaluated the frequency and prognostic impact of DNMT3A mutations (DNMT3A(mut)) in 1770 younger adult patients with acute myeloid leukemia (AML) in the context of other genetic alterations and the European LeukemiaNet (ELN) classification. DNMT3A(mut) were found in 20.9% of AMLs and were associated with older age (P < .0001), higher white blood cell counts (P < .0001), cytogenetically normal AML (CN-AML; P < .0001), NPM1 mutations (P < .0001), FLT3 internal tandem duplications (P < .0001), and IDH1/2 mutations (P < .0001). In univariable and multivariable analyses, DNMT3A(mut) did not impact event-free, relapse-free (RFS), or overall survival (OS) in either the entire cohort or in CN-AML; a negative prognostic effect was found only in the ELN unfavorable CN-AML subset (OS, P = .011). In addition, R882 mutations vs non-R882 mutations showed opposite clinical effects-unfavorable for R882 on RFS (all: hazard ratio [HR], 1.29 [P = .026]; CN-AML: HR, 1.38 [P = .018]) and favorable for non-R882 on OS (all: HR, 0.77 [P = .057]; CN-AML: HR, 0.73 [P = .083]). In our statistically high-powered study with minimized selection bias, DNMT3A(mut) represent a frequent genetic lesion in younger adults with AML but have no significant impact on survival end points; only moderate effects on outcome were found, depending on molecular subgroup and DNMT3A(mut) type